Dearmoring process



Patented Jan. 27, 1925.

UNITED STATES PATENT OFFICE..

THEODORE H. KOHLEB, OF BIIOOMFIELD,

new JERSEY, 'assrenon To sum 0cm LEATHER 00., INC., OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

DEAR-mourns rnocsss.

To all whom it may concern:

Be it known that I, THEODORE H. KoHLnn, a citizen of the United States and residing at Bloomfield, in the county of Essex and State of New Jersey, have invented new and 1m proved Dearmoring Processes, of which the following specification is a full disclosure.

This invention deals with the preparation of shark skins and the like, for commercial uses, and more particularly to a method of treating the skin of armored fish in the production of leather therefrom.

The skins of armored fish, particularly shark skins, possess a physical characteristic that has heretofore been a source of great embarrassment to tanners who have sought to convert such skins into leather. The skin of sharks is protected by a species of armour which is papillate-scabrous in nature and as far as I am aware cannot be removed completely by the methods heretofore available to tanners without injury to the skin. The papillae constituting this armour are each embedded in the epidermis. These apillae comprise minute teeth-like projections on the skin which are very hard, are an excellent abrasive, and under the microscope have the appearance of minute closed fists of a shiny glass-like-appearance, and are commonly referred to as the shagreen. This dermal armour varies in thickness u to one-sixteenth, or even three thirtysecon s, of an inch; depending upon the age of the shark. Such armour is so impenetrable that it is difiicult to sew through it with a needle or easily to sever it with a knife. Accordingly, those engaged in converting the skin, into leather have endeavored to get rid of the armour; but with little success. Attempts have beenmade to grind it off with a suitably-grained emery-wheel, but without success because the wheel merely has the effect of tearing up the grain and removing the superficially projecting portions of the papillae without, however, getting at their roots; which remain as imbedded stumps, so to s eak. A skin roduced in this manner wil not uniform y accept color, inasmuch as the papillae are impene-; trable to color and manifest no tendency to enter into a chemical combination with any of the available dye-stuffs.

Attem ts have likewise been made to treat the who e fish before skinning with boiling water and then to scrape off this armor by Application filed July 23,

means of a knife, as set forth in the Rogers Patent #1,338,531, and also to eliminate it by a chemical action preparatory to tan- .ning as in the Rogers Patent #1,395,7 73, but

such agents as have ,been proposed operate injuriously on the skin itself, gelatinizlng or otherwise impairing it so as to make it practically useless. The impossibility of eliminating this armour has caused tanners to abandon such attempts and to endeavor to produce a useful. leather by subjecting it to metallic tanning agents, such as compounds of chromium; or by resorting to other methods of tanning. The product, however, did not present the grained texture of real leather and was unsatisfactory. Furthermore the coloring materials could not be made to combine with the armour.

This invention, however, proposes a remedy for the aforesaid difiiculties, and it is based upon certain discoveries that I have made as a result of extensive and persistent investigations. I have ascertained that a raw skin, that is, the skinafter removal from the fish, is much less resistant to certain agents than the papillae, and this condition is reversed when both the papillae and the raw skins are subjected to certain (but not all) tanning methods. For example, if the raw skin be subjected to a metallic agent, such as those used in the so-called chrome process-any agent which I have tried-and I have tried nIany-capable of materially affecting the papillae injuriously afiected the tanned skin by decomposing the chromium salt that is, untanning the skin or gelatinizing the chrome-tanned skin. I have made the remarkable discovery, however, that, if a vegetable tanning process be resorted to, no appreciable inversion will take place when the tanned skin and its armour are subjected to the de-armoring agent; although such agent would have destroyed a raw skin or one tanned by a metallic process.

In order that thdse skilled in this art may more thoroughly comprehend the unique principles underlying this discovery and be enabled to put this process into practice, reference will be had to a typical instance of the method preferred by me for treating shark-skins.

The raw skin may first be thoroughly tanned by means of suitable organic tanning sumac, oak, gambier, etc. The tanning methods set forth in the United States Patents Nos. 1,230,266, June 19, 1917, and

resistant thereto in the course of the speci-' fied tanning process. I have discovered that 'hydrochloricacid. when suitably used on a' properlyprepared skin, will answer the purpose of dlslntegratmg or looscnlng the papillac without injuriously a'fi ecting the hide proper.

The next step may. accordingly, be effect I ed advantageously by putting the tanned skins into a tumbling barrel containing a Solution of hydrochloric acid in the proportion of from twenty-two to twenty-four gallons of hydrochloric acid (at 18 Be.) to about five hundred pounds of skin. rotation is continued for two to three hours, with the result that the papillae are loosened or disintegrated andare, by the attrition. separated from the hide, somewhat as a corn may be separated from the ear. and may be washed away as minute nodules. Then Washing is efliect'ed for about an hour by continuing the rotation: using water. Thereby, the acid is-eliminated. The final washing may be accomplished preferably by means of a solution of borax (say one pound of borax for each two hundred pounds of hide) and any residual acid is thereby neutralized;

The hides from the tumbling barrel will be found quite free from any armour and will be perfectly tanned and nowise injured by the treatment. but in a condition to un' dergo any suitable finishing processes. The hide now has a peculiar appearance. It has the natural irregular grained appearance, which is inherent in the natural skin. cov ered throughout with what appears to be minute pores which are the depressions or sock'ets'in which the nodules of the armor formerly were seated. It may be used-in this condition or may be further treated by any of the ordinary finishing processes. The hides now will readily and uniformly accept the coloring material conveniently employed for finished leather and, after this coloring has been done, they may be o1led and dried and are thus made ready for the market.

The resultant leatherdisplays a handsome grained surface entirely devoid of its original armour and is tough and tenacious to an extraordinary #487,211, filed Jul 23, 1921.

The

degree and may be readily cut, sewed, embossed and otherwise worked up into various articles of manu-' facture. The product described herein is claimed in my co-pending application As an alternative to the above-mentioned continuous scale-removing steps, it is quite feasible to apply the acid by hand to the previously-tanned hides by painting a succession of coats of acid on the armoured side at intervals of about six hours until the papillae have become sufiiciently disintegrated and loosened from the epidermis to permit them to be elin'linated by the action of water and a scraping implement. It has been found that the acid mentioned has the efl'ect of rendering the papillae more or less soluble in water, probably by converting them into gelatine so that their removal becomes a simple matter. The agent proposed has the further advantage of being inexpensive, very effective and quick in its action. The principles herein disclosed I believe to be applicable to kindred armoured-skins. such as those of a sword-fish: and other equivalent agents having a differential effect on a differentially-tanned skin may be used, although hydrochloric acid is the agent that I have found best adapted for the purpose.

I therefore claim as new cure by Letters Patent:

. 1. The art of de-armoring a fish skin which comprises tanning the skin and thereafter removing the armor therefrom.

2. The method of producing a scale-free leather from a shark-skin, which consists in differentially tanning the entire skin through the agency of a vegetable tanningbearing material; subsequently subjecting it to an agent to which the thoroughly tanned leather is resistant, whereby the incom letely tanned armour may be disintegrate and its adhesion diminished; and thereafter removing the papillae constituting the armour.

3. The process of treating a fishskin having an armor thereon, which comprises tanning the raw skin into leather with the armor still embedded therein, then treating the skin with an armor-loosening agent and then removing the armor.

4. A process of treating the skin of an armored fish which comprehends the preliminary step of tanning the skin by means of a vegetable tanning compound, subse quently subjecting the skin to the action of an agent adapted to exercise an armor loosening effect, and then removing the armor.

5. A process of treating the skin of an armored fish which comprehends the preliminary ste of tanning the skin by means of a vegeta le tannin com ound, subsequently subjecting the s 'n to t 0 action of a and desire to sehalogen acid adapted to loosen the armor and then removing the said armor.

6. The method of producing a scale-free leather from a shark-skin, which consists in diii'erentially tanning the entire skin through the agency of a vegetable tanning-bearing material; subsequently subjecting it to an acid to which the thoroughly tanned leather is resistant, whereby the incompletely tanned armour may be disintegrated and'its adhesion diminished; and thereafter removing the papillae constituting the armour.

7. The process of treating a fish skin hav ing armor thereon which comprises tanning the raw skin into leather with the armor thereon, then treating the skin with hydrochloric acid thereby rendering the armor readily removable.

8. A tanning process which comprehends the preliminary step of converting a hide into leather by means of a vegetable tanning compound, thereafter subjecting the hide to the action of a hydrochloric acid solution to assist in the removal from the hide of incompletely tanned portions and thereafter removing the said incompletely tanned portions.

9. A process of treating the skin of an armored fish which comprehends the preliminary step of tanning the skin by means of a vegetable tannin compound, subsequently subjecting the s in to the action of an agent adapted to exercise an armorloosening efiect and then removing the armor by attrition.

10. A step in the process of preparing tannedleather from an armored fish skin such as shark, which consists in treating the skin, after removal from the fish but with the armor thereon, with an" armor-loosening agent, and then substantially completely re moving said armor.

11. A step in the process of preparing tanned leather from an armored fish skin s'uch as'shark, which consists in treating the skin, after removal from the fish but with the armor thereon, with an aqueous solution of hydrochloric acid and then substantially completely removing said armor.

In witness whereof, I hereunto subscribe my name, as attested by the two subscribing Witnesses.

THEODORE H. KOI-ILER. Witnesses:

H. S. DATTENHEIR, IRMA SOHNIDER. 

